Heat economy method and apparatus



Aug. 18, 1931. J. o. ROSS HEAT ECONOMY METHOD AND APPARATUS 2Sheets-Sheet 1 Filed Jan. 7, 192

- INVENTOR JZ/m 0 F055 45 214 QM ATTORNEY Aug 18, 1931. 0 oss 1,819,265

HEAT ECONOMY METHOD AND APPARATUS Filed Jan. 7 192 '2 Sheets-Sheet 2 I lH 5 i 1 g l l-l l l R: l

Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE JOHN O. ROSS, OF NEWYORK, N. Y., ASSIGNOR TO J. O. ROSS ENGINEERING CORPO- RATION, OF NEWYORK, N. Y., A. CORPORATION OF NEW YORK HEAT ECONOMY METHOD ANDAPPARATUS Application filed January 7, 1926. Serial No. 79,715.

This invention relates to the artof building ventilation and auxiliarydrying processes; the particular utilization now in mlnd being therecovery of heat from the waste hot air, vapors and gases in paperfactories, and especially the recovery of heat from the waste hot airused for drying coated paper in coating mil-ls.

While I will describe the method and improvements especially as appliedfor use in connection with paper machinery, this utilization is to beconsidered as merely illustrative, for the invention in a broader aspectmay be capable of many other valuable uses in other relations.

An important object of the present invention is to recover heretoforewasted heat in the hot air serving the floater chamber, and at the sametime to make such recovery in a manner to overcome previousdisadvantageous conditions existing not only in that part of the millcontaining the floater chamber but also in accompanyin parts of themill, particularly at levels hig er than the floater chamber. Thesedisadvantageous conditions have been disturbances to the ventilation andundesirable temperature and humidity conditions, resulting from theuncontrolled escape beyond the web of paper in the floater chamber, ofthe hot air dlrected against such web to absorb moisture therefrom.

As is well known, coating is applied to I both sides of the paper at thesame time, in some classes of coated paper. This makes it necessary todry the sheet, at least on the under side, after the sheet leaves thecoating machine and before the sheet touches another tangible or solidsupport. Commonly, the paper sheet issues from the coating machine, topass over a sheet metal chamber equipped with a series of nozzles todischarge heated air under the paper. The velocity and temperature ofthese jets or streams of air are so regulated that not only is the underside of the sheet heated, and sufliciently dried, during passage of thesheet through the chamber, butthe rising air currents 'floatingly suport the paper until it reaches suitable 56 ta e-up rolls, a suctionapron, or the like, at

the far end of the floater. It is desirable to make the chamber as longas possible. Yet the chamber cannot be too long, otherwise there will bedifficulty in floating the paper.

In experiments leading up to the present invention, I have used very hotair on the under side of the sheet passing through the floater chamber.This air, in fact, has been given as high a temperature as ispermissible, steam pressure conditions being considered. In this way,production is speeded up. On the other hand, however, there is always alimit of speed of paper travel to be respected. This speed limit is dueto the fact that the paper must be sufliciently dried, to avoid markingon reaching its solid support beyond the floater chamber. In any event,While the use of very hot air as just explained permits a safe increaseof speed, the amount of waste heat is nevertheless increased. In

other words, while real advantages accrue from the use of very hot air,the previous troubles of heat waste and undesirable working conditionsare aggravated.

The attempt was made to recirculate a good deal of this waste hot air,from the upper ous. If the heated air being blown to float and dry thepaper has a temperature say of 175, and if this air after leaving thepaper heats the room to say 110, a recirculation such as above referredto is not started until 55 of heat are lost by radiation on the build-1ng.

I am aware that others have attempted to erect partitions to close offthe floater chamber and a surrounding working space for the attendants,from the rest of the building, in order to overcome the excessive wasteheat losses; but this arrangement has not overcome radiation andconvection losses, and above all, has not protected the floater chambertenders.

1 chamber.

Another object of the invention is to provide an apparatus wherein hotair or the like, which passes beyond the web of paper in the floaterchamber, is all or practica y all collected and maintained in asubstantially closed system for repeated action through a cycle ofuseful operation. This cycle, starting say from a discharge ofthe heatedair in the usual manner into the floater cham- 2o ber, continues as asuflicient confinement of all or the major part of this air beyond itszone of moisture absorptive activity relative to the paper web to permitthe return of the same to the air heater and thence to a supply fan orequivalent, and is completed by a second discharge of said air in thefloater chamber.

Another object of the invention is to associate with the floater chambera collecting, confining or deflecting means for the waste hot air, andto associate therewith a suitable arrangement, such as an arrangementincluding fans, ducts, valves, dampers, ventilators, by-passes, &c.whereby the waste hot air may be at once kept from rising materiallyabove the floater chamber, and saved, as for return to the usual heater.

A further object of the invention is to provide such a collecting,confining or deflecting means that ready and full inspection of thefloater chamber may be had whenever desired, yet so that normally nomore hot air will escape from the system than about that amount which itis desirable to have escape. In other words, I have found itadvantageous from time to time to add small amounts of sufficiently dryair to the continuous circulation of the invention. In this way, the airin the system never becomes fully satu-' rated and yet practically allof the hot moist air which has been heretofore scattered, is utilizedand reutilized, with a resulting heat economy which is very great. It isim ortant to keep the air in the system enough he ow the completesaturationpoint to have such air dry properly the paper web in thefloater chamber, each time the air repeats its cycle by being dischargedinto the chamber against the web. It is important also, for productionpurposes, to pass the web as rapidly as possible through the floaterchamber. Therefore, the air discharged against the web must not have toogreat a moisture content, if the web. is to dry to the extent previsedduring its passage through the chamber. Thus, the

present object is attained in an ideal way, since I have discovered thatby providing, as the collecting, confining or deflecting meansaforesaid, a hood over the floater chamber equipped with several pendentand raisable flaps of metal, fabric or the like, on one or both sides ofthe hood, these flaps or any one of them may be raised for inspectionpurposes, the whole structure may be of light and mexpensive type, andthe resultant straying off of hot air is just about what is re uired tokeep the salvaged air in the stem a ways properly below the completemoisture saturation oint.

Ot er objects and advantages will become apparent as the apparatus andmethod are described more in detail.

Fig. 1 is a longitudinal cross section more or less diagrammatic, of atypical installation of .an apparatus embodying the invention andadapted for use in carrying out the process. Fig. 2 is a cross sectionof the same alon the lines 22 of Fi 1, and Fig. 3 is a si e elevationmore or ess diagrammatic of the same. i

The following detailed descri tion, therefore,.will be in terms of thei1 ustrated installation, both as to apparatus and method;

although of course it will be-understood that 4 the scope of protectioncontem lated is to be taken solely rom the appende claim, which is to begiven the full range of equivalents.

In the drawings, the paper sheet or web is indicated at 1. This web isshown as issuing from the coating machine 2, and thence passing on forfloatingly su ported advance through or rather over the oater chamber 3.This floater chamber may be of the usual construction, being served withheated air through the duct 5 rising from the heater 6,

oor 7 at a level lower than the floor 8 on a on which the floaterchamber is located. Duct 5 may be equipped with a damper as indicated at9.

In the ordinary installation, the heater delivers the hot air to thesuction blower or supply fan for the floater chamber nozzles; such afan, for instance, as that indicated at 10. In the present case, thisfan is illustrated in such manner that its only inlet is shown as directconnected to the heater. In the present case, further, the fan isillustrated in such manner that its only outlet is shown as directconnected to the duct 5 leading to the floater chamber. Thesearrangements, obviously, are features mer 1y incidental to anarrangement as at present preferred and merely illustratively shown inthe drawings.

The apparatus of the present invention, as an example of the same isillustratively shown in the drawin includes also a hood 11 suitablysuspende or otherwise mounted in place. The hood ma overlie the entire.width and length of the oater chamber, but

I have found that if the hood overlies only about three-quarters of thefloater chamber, there is a 98 or99% heat recovery. This hood acts as acollecting, confining or deflecting means for the waste hot air afterthe same has been discharged to impinge against the under side of thepaper web 1 as the latter passes through the floater chamber.

All or substantially all of the waste hot air thus localized to theimmediate vicinity of the floater chamber is returned according to theinvention in any suitable manner to the stream of hot air being led inthe present instance through the damper controlled duct 5, toward thefloater chamber nozzles. Ac-

, cording to the arrangement illustrated in the drawings, the waste hotair to be thus kept in continuous circulation pursuantto the invention,is passed by way of a return box 12 'to a return duct 13. In the presentcase, this return duct leads direct to the heater 6, and is shown asprovided with a damper '14 for control purposes. Obviously, any othersuitable arrangement for maintaining such continuous circulation of atleast a large part of the waste hot air could be employed.

- Combined ventilation and inspection means are preferably carried bythe hood. Such means may comprise a plurality of flaps, such as the oneshown at 16. These flaps or equivalents, may be provided to any numberdesired, at one or both sides of the hood. They may be simply plate orsheet members or structures hingedly suspended at their tops asindicated at 17, normally hanging in substantially vertical planes bytheir own weight and thus held to closed position merely by gravity.They may more or less, or even incompletely, overlap suitable cut-awayportions of the hood constituting openings therein, such an opening isindicated in the drawings at 18. Any one of these flaps may be raised byan attendant at any instant required or thought advisable. It has beenfound that a flap is required to be raised, just about as many timesduring a given run, and for just long enough each time, to bring aboutthe straying ofl' of that really inconsequential amount of Waste hot airrequired to operate the system according to the method 'of the inventionwith maximum heat economy and without discomfort to the floater roomtenders and those working at other points in the mill.

The method of the invention, whether or not facilitated by an apparatusof the general class of that just described, will thus be seen toinvolve the handling of a flow of hot air, vapors or gases, directedtoward a particular and restricted zone of action characteristic of theindustrial process involved, in a manner to bring about great heateconomies and maximum comfort to the workmen. The

method broadly comprises, in its preferred form, localizing at least thegreater part of such air, vapors and gases to said zone, removing themtherefrom before the straying otf of a considerable number of heatunits, and blending all or substantially all of the removed fluids witha stream of similar fluids approaching said zone; and indefinitelyrepeating the cycle described to give suiiicient length of time to drythe top side after the drying of the under side by the action of thefloater chamber. \Vith the present great increase in speeds of coating,however, any drying of the upper side of the sheet while the latter isfloating is of great value in minimizing the amount of heat and spacerequired for drying the top side. This top side dries very little whilethe sheet is passingthrough the previous open floater chamber. When ahood is used pursuant to the present invention, however, air at ahighertemperature is kept in contact with the top of the sheet, and theincreased drying of the latter is very apparent.

It is again to be emphasized that the invention is not to be limited, asto apparatus, by any particular apparatus or devices herein illustratedand herein above described; nor, as to method, by anything hereinabovesaid. In other words, the sole measure of protection contemplated is tobe found in the follow claim, in every case where clear and unambiguousdefinitions are therein set forth.

I claim:

An apparatus of the character described including, in combination, aduct, said duct providing the under side of a floater chamher, a hoodproviding the upper portion of said chamber. said chamber receiving aweb of material disposed between said duct and said hood, means forforcing air under pressure through said duct and solely against theunder side of said web and with the faces out of contact with said ductand hood, said hood being provided with an opening for the flow of airescaping from said duct and past said web, and a further duct connectedto said hood opening and also connected to said air impelling means toreturn the escaped air thereto.

JOHN O. ROSS.

